#807: Browse for Themes brings a template's slide master and layouts

Design › Browse for Themes… with a .pptx or .potx now does what PowerPoint
does: the file's first slide master and its layouts replace the master the
current slide uses (a preserved master stays beside it), stretched to this
deck's slide size. Each slide on the old master moves to the new layout with
the same name, else the same kind, and keeps its content as Layout does. One
undo step. A .thmx still brings its theme only.

Reuse Slides' master copy (media, fresh master, layout and shape ids) moves
into reuse::import_master so both commands share it.

Co-Authored-By: Claude Code <noreply@anthropic.com>



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# Changes to be committed:
#	modified:   ROADMAP.md
#	modified:   crates/engine/src/cmd/design.rs
#	modified:   crates/engine/src/cmd/reuse.rs
#	modified:   docs/file-format-parity.md
#

crates/engine/src/cmd/design.rs

@@ -20,7 +20,7 @@ pub fn specs() -> Vec<CommandSpec> {
             "Browse for Themes…",
             ["Design", "Themes"],
             None,
-            "{path} | {name, data: base64} — apply the theme of a .thmx, .pptx or .potx file",
+            "{path} | {name, data: base64} — apply a .pptx or .potx's slide master and layouts (slides move to the matching layouts), or a .thmx's theme",
             has_doc,
             browse_theme
         ),
@@ -160,6 +160,13 @@ fn browse_theme(s: &mut Session, p: &Value) -> Result<Value> {
     if !deckcraft_pptx::sniff(&bytes) {
         return Err(bad("design.browseTheme", "not a theme or PowerPoint file"));
     }
+    // A presentation or template brings its slide master and layouts, as in PowerPoint; a .thmx
+    // (its main part is a theme, not a presentation) brings the theme alone.
+    if let Ok(src) = super::file::open_presentation("theme.pptx", &bytes)
+        && src.masters.first().is_some_and(|m| !m.layouts.is_empty())
+    {
+        return apply_master(s, &src);
+    }
     let (theme, media) = deckcraft_pptx::import_theme(&bytes).map_err(|e| bad("design.browseTheme", e.to_string()))?;
     let name = theme.name.clone();
     s.edit(|doc, sel| {
@@ -179,6 +186,58 @@ fn browse_theme(s: &mut Session, p: &Value) -> Result<Value> {
     Ok(json!({"theme": name}))
 }
 
+/// Design › Browse for Themes… with a `.pptx` / `.potx`: its first master and layouts replace the
+/// master the current slide uses (a preserved master stays beside it), stretched to this deck's
+/// slide size. Each slide on it moves to the new layout with the same name, else the same kind,
+/// keeping its content as Layout does.
+fn apply_master(s: &mut Session, src: &Presentation) -> Result<Value> {
+    let from = src.masters.first().ok_or_else(|| bad("design.browseTheme", "no master"))?;
+    let theme = from.theme.name.clone();
+    s.edit(|doc, sel| {
+        let mi = master_index(doc, sel);
+        let old = doc.masters.get(mi).cloned().ok_or_else(|| bad("design.browseTheme", "no master"))?;
+        let (mut media, mut layouts) = Default::default();
+        let mut m = super::reuse::import_master("design.browseTheme", doc, src, from, &mut media, &mut layouts)?;
+        let (sx, sy) = (doc.slide_size.width / src.slide_size.width.max(1.0), doc.slide_size.height / src.slide_size.height.max(1.0));
+        if (sx - 1.0).abs() > 1e-9 || (sy - 1.0).abs() > 1e-9 {
+            scale_shapes(&mut m.shapes, sx, sy, 1.0, 0.0, 0.0);
+            for l in &mut m.layouts {
+                scale_shapes(&mut l.shapes, sx, sy, 1.0, 0.0, 0.0);
+            }
+        }
+        let moves: Vec<(usize, deckcraft_model::LayoutId)> =
+            doc.slides.iter().enumerate().filter_map(|(i, sl)| old.layout(sl.layout).and_then(|l| matching_layout(&m, l)).map(|l| (i, l))).collect();
+        let layouts = m.layouts.len();
+        if old.preserve {
+            doc.masters.insert(mi, Arc::new(m));
+        } else if let Some(slot) = doc.masters.get_mut(mi) {
+            *slot = Arc::new(m);
+        }
+        for (i, l) in &moves {
+            super::slide::apply_layout(doc, *i, *l)?;
+        }
+        if let Target::Layout { master, .. } = sel.target {
+            sel.target = Target::Master { master };
+        }
+        sel.shapes.clear();
+        sel.text = None;
+        Ok(json!({"theme": theme, "layouts": layouts, "slides": moves.len()}))
+    })
+}
+
+/// The layout of `m` a slide on `from` moves to: same name, else same kind (not for custom
+/// layouts), else Title and Content, else the first.
+fn matching_layout(m: &deckcraft_model::Master, from: &deckcraft_model::Layout) -> Option<deckcraft_model::LayoutId> {
+    use deckcraft_model::LayoutType;
+    let ls = &m.layouts;
+    ls.iter()
+        .find(|l| !from.name.is_empty() && l.name.trim().eq_ignore_ascii_case(from.name.trim()))
+        .or_else(|| ls.iter().find(|l| from.kind != LayoutType::Custom && l.kind == from.kind))
+        .or_else(|| ls.iter().find(|l| l.kind == LayoutType::TitleAndContent))
+        .or_else(|| ls.first())
+        .map(|l| l.id)
+}
+
 /// `theme` with every `media` id field rewritten through `map` (format-scheme picture fills).
 fn remap_media_ids(theme: &deckcraft_model::theme::Theme, map: &std::collections::HashMap<u32, u32>) -> Result<deckcraft_model::theme::Theme> {
     fn rec(v: &mut Value, map: &std::collections::HashMap<u32, u32>, depth: usize) {
@@ -1731,8 +1790,10 @@ mod tests {
 
 #[cfg(test)]
 mod browse_theme_tests {
-    use deckcraft_model::PhType;
+    use std::sync::Arc;
+
     use deckcraft_model::text::RunKind;
+    use deckcraft_model::{Background, Fill, PhType};
     use serde_json::json;
 
     use crate::{Session, Target};
@@ -1758,6 +1819,108 @@ mod browse_theme_tests {
         assert!(s.execute("design.browseTheme", &json!({})).is_err());
     }
 
+    /// A 4:3 brand template: a logo and a background on the master, its layouts renamed (so slides
+    /// can only find them by kind) and its content layout's title moved.
+    fn brand_template() -> (String, Vec<u8>, deckcraft_model::Xfrm) {
+        let mut img = image::RgbaImage::new(2, 2);
+        img.put_pixel(0, 0, image::Rgba([200, 20, 30, 255]));
+        let mut logo = Vec::new();
+        image::DynamicImage::ImageRgba8(img).write_to(&mut std::io::Cursor::new(&mut logo), image::ImageFormat::Png).unwrap();
+        let mut t = Session::with_new();
+        t.execute("design.slideSize", &json!({"preset": "standard", "scale": "none"})).unwrap();
+        let title = t
+            .edit(|doc, _| {
+                let media = doc.add_media("logo.png", "image/png", logo.clone()).unwrap();
+                let id = deckcraft_model::ShapeId(doc.alloc_id().unwrap());
+                let m = Arc::make_mut(doc.masters.get_mut(0).unwrap());
+                m.shapes.push(deckcraft_model::Shape {
+                    id,
+                    name: "Logo".into(),
+                    kind: deckcraft_model::ShapeKind::Picture { fill: deckcraft_model::style::PictureFill { media, ..Default::default() } },
+                    xfrm: Some(deckcraft_model::Xfrm { x: 600.0, y: 20.0, w: 100.0, h: 40.0, ..Default::default() }),
+                    ..Default::default()
+                });
+                m.background =
+                    Some(Background::Fill { fill: Fill::solid(deckcraft_model::ColorRef::rgb(deckcraft_color::Rgba::rgb(0x0A, 0x2B, 0x4C))) });
+                for l in &mut m.layouts {
+                    l.name = format!("Brand {}", l.name);
+                }
+                let obj = m.layouts.iter_mut().find(|l| l.kind == deckcraft_model::LayoutType::TitleAndContent).unwrap();
+                let title = obj.shapes.iter_mut().find(|sh| sh.ph_type().is_some_and(PhType::is_title)).unwrap();
+                let x = deckcraft_model::Xfrm { x: 72.0, y: 400.0, w: 576.0, h: 80.0, ..Default::default() };
+                title.xfrm = Some(x);
+                Ok(x)
+            })
+            .unwrap();
+        (crate::cmd::base64_encode(&deckcraft_pptx::export_as(&t.doc().unwrap().doc, "potx").unwrap()), logo, title)
+    }
+
+    #[test]
+    fn a_template_brings_its_master_and_layouts_and_slides_follow() {
+        let (data, logo, title) = brand_template();
+        let mut s = Session::with_new();
+        s.execute("slide.new", &json!({"layout": "titleAndContent", "title": "Agenda", "body": "Point one"})).unwrap();
+        let before = s.doc().unwrap().doc.clone();
+        let n = undo_len(&s);
+        let r = s.execute("design.browseTheme", &json!({"name": "Brand.potx", "data": data})).unwrap();
+        assert_eq!(r["slides"], json!(2), "{r}");
+        assert_eq!(undo_len(&s), n + 1, "one undo step");
+
+        let doc = &s.doc().unwrap().doc;
+        assert!(doc.validate().is_empty(), "{:?}", doc.validate());
+        assert_eq!(doc.masters.len(), 1, "the old master is replaced");
+        let m = &doc.masters[0];
+        assert_ne!(m.id, before.masters[0].id);
+        assert!(m.layouts.iter().all(|l| l.name.starts_with("Brand ")));
+        assert!(matches!(m.background, Some(Background::Fill { fill: Fill::Solid { .. } })));
+        let pic = m.shapes.iter().find(|sh| sh.name == "Logo").expect("the master's logo comes along");
+        let deckcraft_model::ShapeKind::Picture { fill } = &pic.kind else { panic!("logo is a picture") };
+        assert_eq!(doc.media(fill.media).map(|m| m.data.as_ref().clone()), Some(logo));
+        // The 4:3 master stretches to this deck's 16:9.
+        let k = doc.slide_size.width / 720.0;
+        let px = pic.xfrm.unwrap();
+        assert!((px.x - 600.0 * k).abs() < 0.01 && (px.w - 100.0 * k).abs() < 0.01 && (px.y - 20.0).abs() < 0.01, "{px:?}");
+
+        // Each slide moved to the brand layout of its kind, and kept its text.
+        for (old, new) in before.slides.iter().zip(&doc.slides) {
+            let (_, was) = before.layout(old.layout).unwrap();
+            let (owner, now) = doc.layout(new.layout).expect("on a layout of the new master");
+            assert_eq!(owner.id, m.id);
+            assert_eq!(now.kind, was.kind);
+        }
+        let agenda = doc.slides.iter().find(|sl| sl.shapes.iter().any(|sh| sh.text.as_ref().is_some_and(|t| t.text() == "Agenda"))).unwrap();
+        assert!(agenda.shapes.iter().any(|sh| sh.text.as_ref().is_some_and(|t| t.text() == "Point one")));
+        let (_, lay) = doc.layout(agenda.layout).unwrap();
+        let lt = lay.shapes.iter().find(|sh| sh.ph_type().is_some_and(PhType::is_title)).unwrap().xfrm.unwrap();
+        assert!((lt.x - title.x * k).abs() < 0.01 && (lt.y - title.y).abs() < 0.01, "{lt:?}");
+        let st = agenda.shapes.iter().find(|sh| sh.ph_type().is_some_and(PhType::is_title)).unwrap();
+        assert!(st.xfrm.is_none(), "the slide title follows the new layout");
+
+        s.execute("edit.undo", &json!({})).unwrap();
+        let doc = &s.doc().unwrap().doc;
+        assert_eq!(doc.masters, before.masters);
+        assert_eq!(doc.slides, before.slides);
+    }
+
+    #[test]
+    fn a_preserved_master_stays_beside_the_template() {
+        let (data, _, _) = brand_template();
+        let mut s = Session::with_new();
+        s.execute("view.slideMaster", &json!({"master": 0, "layout": 1})).unwrap();
+        s.execute("master.preserve", &json!({"preserve": true})).unwrap();
+        s.execute("view.slideMaster", &json!({"master": 0})).unwrap();
+        s.execute("master.preserve", &json!({"preserve": true})).unwrap();
+        let old = s.doc().unwrap().doc.masters[0].id;
+        s.execute("view.slideMaster", &json!({"master": 0, "layout": 1})).unwrap();
+        s.execute("design.browseTheme", &json!({"name": "Brand.pptx", "data": data})).unwrap();
+        let st = s.doc().unwrap();
+        assert_eq!(st.doc.masters.len(), 2);
+        assert_eq!(st.doc.masters[1].id, old);
+        assert_eq!(st.selection.target, Target::Master { master: 0 }, "Slide Master view shows the new master");
+        let new = &st.doc.masters[0];
+        assert!(st.doc.slides.iter().all(|sl| new.layout(sl.layout).is_some()));
+    }
+
     fn undo_len(s: &crate::Session) -> usize {
         s.doc().unwrap().history.undo.len()
     }

crates/engine/src/cmd/reuse.rs

@@ -10,7 +10,7 @@ use std::collections::HashMap;
 use std::sync::Arc;
 
 use deckcraft_model::text::{Action, Hyperlink, RunProps, TextBody};
-use deckcraft_model::{LayoutId, MasterId, MediaId, Presentation, ShapeId, ShapeKind, Slide, SlideId};
+use deckcraft_model::{LayoutId, Master, MasterId, MediaId, Presentation, ShapeId, ShapeKind, Slide, SlideId};
 use serde_json::{Value, json};
 
 use super::*;
@@ -114,9 +114,9 @@ fn relink_shapes(shapes: &mut [deckcraft_model::Shape], map: &HashMap<SlideId, S
 }
 
 /// Fresh shape ids for `shapes`, and the old → new map.
-fn renumber(doc: &mut Presentation, shapes: &mut [deckcraft_model::Shape]) -> Result<HashMap<ShapeId, ShapeId>> {
+fn renumber(cmd: &str, doc: &mut Presentation, shapes: &mut [deckcraft_model::Shape]) -> Result<HashMap<ShapeId, ShapeId>> {
     let old = shape_ids(shapes);
-    super::edit::reid("slide.reuse", doc, shapes)?;
+    super::edit::reid(cmd, doc, shapes)?;
     let map: HashMap<ShapeId, ShapeId> = old.into_iter().zip(shape_ids(shapes)).collect();
     remap_connectors(shapes, &map, 0);
     Ok(map)
@@ -171,19 +171,7 @@ fn reuse(s: &mut Session, p: &Value) -> Result<Value> {
                     continue;
                 }
                 masters_done.push(m.id);
-                let mut used = vec![];
-                media_refs::visit::master(m, &mut |id: &MediaId| used.push(*id));
-                copy_media(doc, &src, &used, &mut media_map)?;
-                let mut m = m.clone();
-                media_refs::visit_mut::master(&mut m, &mut remap(&media_map));
-                m.id = MasterId(doc.alloc_id().ok_or_else(|| bad("slide.reuse", NO_ID_SPACE))?);
-                renumber(doc, &mut m.shapes)?;
-                for l in &mut m.layouts {
-                    let new = LayoutId(doc.alloc_id().ok_or_else(|| bad("slide.reuse", NO_ID_SPACE))?);
-                    layout_map.insert(l.id, new);
-                    l.id = new;
-                    renumber(doc, &mut l.shapes)?;
-                }
+                let m = import_master("slide.reuse", doc, &src, m, &mut media_map, &mut layout_map)?;
                 doc.masters.push(Arc::new(m));
             }
         }
@@ -192,11 +180,11 @@ fn reuse(s: &mut Session, p: &Value) -> Result<Value> {
         let mut slide_map: HashMap<SlideId, SlideId> = HashMap::new();
         for &i in &picked {
             let Some(from) = src.slides.get(i) else { continue };
-            copy_media(doc, &src, &media_refs::slide_media(from), &mut media_map)?;
+            copy_media("slide.reuse", doc, &src, &media_refs::slide_media(from), &mut media_map)?;
             let mut sl: Slide = from.as_ref().clone();
             media_refs::visit_mut::slide(&mut sl, &mut remap(&media_map));
             sl.id = SlideId(doc.alloc_id().ok_or_else(|| bad("slide.reuse", NO_ID_SPACE))?);
-            let map = renumber(doc, &mut sl.shapes)?;
+            let map = renumber("slide.reuse", doc, &mut sl.shapes)?;
             for a in &mut sl.animations {
                 a.shape = map.get(&a.shape).copied().unwrap_or(a.shape);
                 a.trigger = a.trigger.map(|t| map.get(&t).copied().unwrap_or(t));
@@ -227,9 +215,35 @@ fn reuse(s: &mut Session, p: &Value) -> Result<Value> {
     })
 }
 
+/// A copy of `src`'s master `m` ready to join `doc`: its media copied in, fresh master, layout and
+/// shape ids. `layouts` gains each source layout id → its copy's.
+pub(crate) fn import_master(
+    cmd: &str,
+    doc: &mut Presentation,
+    src: &Presentation,
+    m: &Master,
+    media_map: &mut HashMap<MediaId, MediaId>,
+    layouts: &mut HashMap<LayoutId, LayoutId>,
+) -> Result<Master> {
+    let mut used = vec![];
+    media_refs::visit::master(m, &mut |id: &MediaId| used.push(*id));
+    copy_media(cmd, doc, src, &used, media_map)?;
+    let mut m = m.clone();
+    media_refs::visit_mut::master(&mut m, &mut remap(media_map));
+    m.id = MasterId(doc.alloc_id().ok_or_else(|| bad(cmd, NO_ID_SPACE))?);
+    renumber(cmd, doc, &mut m.shapes)?;
+    for l in &mut m.layouts {
+        let new = LayoutId(doc.alloc_id().ok_or_else(|| bad(cmd, NO_ID_SPACE))?);
+        layouts.insert(l.id, new);
+        l.id = new;
+        renumber(cmd, doc, &mut l.shapes)?;
+    }
+    Ok(m)
+}
+
 /// Copy the source media `used` into `doc` under fresh ids, once each (identical bytes already in
 /// `doc` are shared; a linked item keeps its link).
-fn copy_media(doc: &mut Presentation, src: &Presentation, used: &[MediaId], map: &mut HashMap<MediaId, MediaId>) -> Result<()> {
+fn copy_media(cmd: &str, doc: &mut Presentation, src: &Presentation, used: &[MediaId], map: &mut HashMap<MediaId, MediaId>) -> Result<()> {
     for &id in used {
         if map.contains_key(&id) {
             continue;
@@ -237,12 +251,12 @@ fn copy_media(doc: &mut Presentation, src: &Presentation, used: &[MediaId], map:
         let Some(m) = src.media(id) else { continue };
         let new = if m.link.is_some() {
             let mut item = m.clone();
-            item.id = MediaId(doc.alloc_id().ok_or_else(|| bad("slide.reuse", NO_ID_SPACE))?);
+            item.id = MediaId(doc.alloc_id().ok_or_else(|| bad(cmd, NO_ID_SPACE))?);
             let new = item.id;
             doc.media.push(item);
             new
         } else {
-            doc.add_media(&m.name, &m.content_type, m.data.as_ref().clone()).ok_or_else(|| bad("slide.reuse", NO_ID_SPACE))?
+            doc.add_media(&m.name, &m.content_type, m.data.as_ref().clone()).ok_or_else(|| bad(cmd, NO_ID_SPACE))?
         };
         map.insert(id, new);
     }